"The trees are sprayed frequently with chemicals and next month they will go
on sale as locally grown organic trees. "

Well if they are spraying with something like soap solution for aphids, then
they would have to spray weekly, where as if using a good organo-phosphorus
based spray then once every month or 2 would be enough.

Probably more risk from the lights on the artificial tree heating the
"Plastic" and giving off free radical polymers.
A good fresh tree with the cut end in water for all its time in the house
will be more beneficial, the humidity and the small amount of resin in the
air will be of benefit to your chest and help to make breathing easier.



--
David Hill
Abacus Nurseries
www.abacus-nurseries.co.uk